/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2002,2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xerces.internal.impl.dv.util;

/**
 * format validation
 *
 * This class encodes/decodes hexadecimal data
 *
 * @author Jeffrey Rodriguez
 * @xerces.internal
 */
public final class HexBin {

  static private final int BASELENGTH = 128;
  static private final int LOOKUPLENGTH = 16;
  static final private byte[] hexNumberTable = new byte[BASELENGTH];
  static final private char[] lookUpHexAlphabet = new char[LOOKUPLENGTH];


  static {
    for (int i = 0; i < BASELENGTH; i++) {
      hexNumberTable[i] = -1;
    }
    for (int i = '9'; i >= '0'; i--) {
      hexNumberTable[i] = (byte) (i - '0');
    }
    for (int i = 'F'; i >= 'A'; i--) {
      hexNumberTable[i] = (byte) (i - 'A' + 10);
    }
    for (int i = 'f'; i >= 'a'; i--) {
      hexNumberTable[i] = (byte) (i - 'a' + 10);
    }

    for (int i = 0; i < 10; i++) {
      lookUpHexAlphabet[i] = (char) ('0' + i);
    }
    for (int i = 10; i <= 15; i++) {
      lookUpHexAlphabet[i] = (char) ('A' + i - 10);
    }
  }

  /**
   * Encode a byte array to hex string
   *
   * @param binaryData array of byte to encode
   * @return return encoded string
   */
  static public String encode(byte[] binaryData) {
    if (binaryData == null) {
      return null;
    }
    int lengthData = binaryData.length;
    int lengthEncode = lengthData * 2;
    char[] encodedData = new char[lengthEncode];
    int temp;
    for (int i = 0; i < lengthData; i++) {
      temp = binaryData[i];
      if (temp < 0) {
        temp += 256;
      }
      encodedData[i * 2] = lookUpHexAlphabet[temp >> 4];
      encodedData[i * 2 + 1] = lookUpHexAlphabet[temp & 0xf];
    }
    return new String(encodedData);
  }

  /**
   * Decode hex string to a byte array
   *
   * @param encoded encoded string
   * @return return array of byte to encode
   */
  static public byte[] decode(String encoded) {
    if (encoded == null) {
      return null;
    }
    int lengthData = encoded.length();
    if (lengthData % 2 != 0) {
      return null;
    }

    char[] binaryData = encoded.toCharArray();
    int lengthDecode = lengthData / 2;
    byte[] decodedData = new byte[lengthDecode];
    byte temp1, temp2;
    char tempChar;
    for (int i = 0; i < lengthDecode; i++) {
      tempChar = binaryData[i * 2];
      temp1 = (tempChar < BASELENGTH) ? hexNumberTable[tempChar] : -1;
      if (temp1 == -1) {
        return null;
      }
      tempChar = binaryData[i * 2 + 1];
      temp2 = (tempChar < BASELENGTH) ? hexNumberTable[tempChar] : -1;
      if (temp2 == -1) {
        return null;
      }
      decodedData[i] = (byte) ((temp1 << 4) | temp2);
    }
    return decodedData;
  }
}
